Radio amplifier for low frequencies



Nov. 28, 1933. R. GUNN 1,936,597

RADIO AMPLIFIER FOR LOW FREQUENCIES Filed Nov. 12, 1931 INVENTOR R055 Gun n ATTORNEY Patented Nov. 28, 1933 uNirsn stares rant 1,936,597 RADIO AMILIFIER FOR LQW FREQUENCZES Ross Gunn, Washington, D. 0.

Application November 12, 1931 Serial No. 574,570

9 Claims. (01. 179-171) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) My invention relates to an amplifying device for radio, and more particularly to one especially adapted for use over substantially the whole range of frequencies used in that art, and therefore available for use with low frequencies.

It is the object of this invention to provide an amplifier that embodies a novel means of regenerative amplification that will function satisfactorily with practically all wave lengths used in radio communication.

The single' figure of the drawing shows diagrammatically a circuit that embodies the present invention.

It is Well known that the resistance coupled amplifier is the most satisfactory one for receiving waves over a wide range of frequencies and I have therefore used that type of coupling in this device.

The wires leading to the input are designated by 1 and 2, the former being connected to the grid 3 of vacuum tube 4, the tube being of the well known four element type having a filament 5, plate 6, and shield grid 7. Tube 4 is coupled to a tube 8 having grid 9, plate 10, filament l1, and shield grid 12, through resistance 13 that is preferably of the order of three to ten megohms, the resistance being connected to the battery 14 that is the common source of plate potential for both plates, and to plate 6. Battery 15 is a source of potential for grid 3, the mean value of the potential of the grid being controlled by a voltage divider or potentiorneter 16. Shield grid 7 is maintained at a positive potential by a low voltage battery 17, lay-passed by a suitable condenser 1%.

Grid 9 of tube 8 is connected to the output circuit of tube 4 through battery 19 which'iinpresses the desired negative potential on the grid. Plate 10 is connected to output wire 29,

and the other output wire, designated by 21, is variably connectedto battery 1%. Shield grid 12 is connected to the positive terminal of battery 22, the negative terminal of which has a variable connection through wire 25 with resistance 23 that is connected to the negative terminal of filament 5. Resistance 23 is connected to potentiometer 16 through wire 24 that has a variable connection with the resistance 23, and hence the variations of the current in the circuit of I'shielcl grid 12 induced bychanges of the potential on control grid 9 will result in proportional changes in the voltage drop over that portion of resistance 23 between the contacts of wires 24 and 25 with that resistance. The said changes in voltage drop in resistance 23 will be impressed upon control grid 3 of tube 4:, thus giving a regenerative action.

it will be understood that the above description and accompanying drawing comprehend only the gener and preferred embodiment of $0 invention, d that various changes in construction, proportion and arrangement of parts may be niade within the scope of the appended claims, and without sacrificing any of the advantages of my invention.

The herein described invention may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to me of any royalties thereon.

Having thus described my invention, what I claim is:

1. A radio amplifying device, comprising a four-element vacuum tube having a filament, a control grid, a shield grid, and a plate; a resist- 7 ance and a battery connected in series between said plate and said filament, a second battery connected between said shield grid and said filament, a by-pass condenser connected to said s ld grid circuit between said battery and said shield grid to said filament, a second foureleinent tube having a control grid, a third battery connected to the control grid of said second tube and to the plate circuit of the first tube, a shield grid in said second tube, a second resistance connected to the filament of the first tube, a fourth battery connected to the'shield grid of the second tube and to the second resistance, a plate in said second tube connected to an output circuit, means variably connecting said output circuit with said first battery, a fifth battery, a potentiometer connected thereto and to the control grid circuit of the first tube, and cans connecting the said potentiometer to said second resistance between the said filament of the first tube and the connection of said resistance to the said fourth battery.

2. A radio amplifying device, comprising two four-element vacuum tubes, each having a filament, a control grid, a shield grid, and a plate; 100 a resistance connected between the plate and the filament of the first of said tubes, means connecting the control grid of the second tube. to

the plate circuit of the first tube, a second resistance connected to the filament of the first 105,.

meeting said potentiometer to said second re sistance between said filament and the connection of the shield grid of the second tube thereto.

3. A radio amplifying device, comprising two four-element vacuum tubes, each having a filament, a control grid, a shield grid, and a plate; resistance coupling means between said tubes, a resistance connected at one end to the filament of the first tube, means connecting the shield grid of the second tube to said resistance adjacent the other end thereof, and means variably connecting said resistance intermediate its ends to the grid circuit of the first tube.

4. A radio amplifying device, comprising two four-element vacuum tubes, each having a filament, a control grid, a shield grid, and a plate; coupling means between said tubes, a resistance connected at one end to the filament of the first tube, means connecting. the shield grid of the second tube to said resistance adjacent the other end thereof and means variably connecting said resistance intermediate its ends to the grid circuit of the first tube.

5. A radio amplifying device, comprising two four-element vacuum tubes, each having a filament, a control grid, a shield grid, and a plate; resistance coupling means between said tubes, a circuit including the shield grid of the second tube and means operatively connecting said shield grid to the first tube and means whereby the voltage across a portion of the said circuit may be impressed upon the control grid of the first tube.

6. A radio amplifying device, comprising two four-element vacuum tubes, each having a filament, 2. control grid, a shield grid, and a plate; coupling means between said tubes, a circuit including the shield grid of the second tube and means operatively connecting said shield grid to the first tube and means whereby the voltage across a portion of said circuit may be impressed upon the control grid of the first tube.

2'7. A radio amplifying device, comprising two shield grid vacuum'tubes, coupling means between said tubes, a resistance element in the shield grid circuit of the second of said tubes, and means whereby the voltage across a portion of said element may be impressed upon the control grid of the first tube.

8. A radio amplifying device, comprising two shield grid vacuum tubes, coupling means between said tubes, means operatively connecting the shield grid of the second tube to the first tube and means for impressing on the control grid of the first tube the voltage across a portion of the first mentioned means.

9. A radio amplifying device, comprising two shield grid vacuum tubes, coupling means between said tubes, means connecting the shield grid of the second tube to the filament of the first tube and means for impressing on the control grid of the first tube the voltage across a. portion of the first mentioned means.

ROSS GUNNL 

